Codestring i ="/n";
string m ="3";
Regex r =new Regex(@"/D");
//同Regex r = new Regex("//D");
//r.IsMatch(i)结果:true
//r.IsMatch(m)结果:falsestring i ="%";
string m ="3";
Regex r =new Regex("[a-z0-9]");
//匹配小写字母或数字字符
//r.IsMatch(i)结果:false
//r.IsMatch(m)结果:true
Codestring i ="Live for nothing,die for something";
Regex r1 =new Regex("^Live for nothing,die for something$");
//r1.IsMatch(i) trueRegex r2 =new Regex("^Live for nothing,die for some$");
//r2.IsMatch(i) falseRegex r3 =new Regex("^Live for nothing,die for some");
//r3.IsMatch(i) truestring i =@"Live for nothing,
die for something";//多行Regex r1 =new Regex("^Live for nothing,die for something$");
Console.WriteLine("r1 match count:"+ r1.Matches(i).Count);//0Regex r2 =new Regex("^Live for nothing,die for something$", RegexOptions.Multiline);
Console.WriteLine("r2 match count:"+ r2.Matches(i).Count);//0Regex r3 =new Regex("^Live for nothing,/r/ndie for something$");
Console.WriteLine("r3 match count:"+ r3.Matches(i).Count);//1Regex r4 =new Regex("^Live for nothing,$");
Console.WriteLine("r4 match count:"+ r4.Matches(i).Count);//0Regex r5 =new Regex("^Live for nothing,$", RegexOptions.Multiline);
Console.WriteLine("r5 match count:"+ r5.Matches(i).Count);//0Regex r6 =new Regex("^Live for nothing,/r/n$");
Console.WriteLine("r6 match count:"+ r6.Matches(i).Count);//0Regex r7 =new Regex("^Live for nothing,/r/n$", RegexOptions.Multiline);
Console.WriteLine("r7 match count:"+ r7.Matches(i).Count);//0Regex r8 =new Regex("^Live for nothing,/r$");
Console.WriteLine("r8 match count:"+ r8.Matches(i).Count);//0Regex r9 =new Regex("^Live for nothing,/r$", RegexOptions.Multiline);
Console.WriteLine("r9 match count:"+ r9.Matches(i).Count);//1Regex r10 =new Regex("^die for something$");
Console.WriteLine("r10 match count:"+ r10.Matches(i).Count);//0Regex r11 =new Regex("^die for something$", RegexOptions.Multiline);
Console.WriteLine("r11 match count:"+ r11.Matches(i).Count);//1Regex r12 =new Regex("^");
Console.WriteLine("r12 match count:"+ r12.Matches(i).Count);//1Regex r13 =new Regex("$");
Console.WriteLine("r13 match count:"+ r13.Matches(i).Count);//1Regex r14 =new Regex("^", RegexOptions.Multiline);
Console.WriteLine("r14 match count:"+ r14.Matches(i).Count);//2Regex r15 =new Regex("$", RegexOptions.Multiline);
Console.WriteLine("r15 match count:"+ r15.Matches(i).Count);//2Regex r16 =new Regex("^Live for nothing,/r$/n^die for something$", RegexOptions.Multiline);
Console.WriteLine("r16 match count:"+ r16.Matches(i).Count);//1
//对于一个多行字符串,在设置了Multiline选项之后,^和$将出现多次匹配。string i ="Live for nothing,die for something";
string m ="Live for nothing,die for some thing";
Regex r1 =new Regex(@"/bthing/b");
Console.WriteLine("r1 match count:"+ r1.Matches(i).Count);//0Regex r2 =new Regex(@"thing/b");
Console.WriteLine("r2 match count:"+ r2.Matches(i).Count);//2Regex r3 =new Regex(@"/bthing/b");
Console.WriteLine("r3 match count:"+ r3.Matches(m).Count);//1Regex r4 =new Regex(@"/bfor something/b");
Console.WriteLine("r4 match count:"+ r4.Matches(i).Count);//1
///b通常用于约束一个完整的单词
Codestring x ="1024";
string y ="+1024";
string z ="1,024";
string a ="1";
string b="-1024";
string c ="10000";
Regex r =new Regex(@"^/+?[1-9],?/d{3}$");
Console.WriteLine("x match count:"+ r.Matches(x).Count);//1Console.WriteLine("y match count:"+ r.Matches(y).Count);//1Console.WriteLine("z match count:"+ r.Matches(z).Count);//1Console.WriteLine("a match count:"+ r.Matches(a).Count);//0Console.WriteLine("b match count:"+ r.Matches(b).Count);//0Console.WriteLine("c match count:"+ r.Matches(c).Count);//0
//匹配1000到9999的整数。
Codestring x ="0";
string y ="0.23";
string z ="100";
string a ="100.01";
string b ="9.9";
string c ="99.9";
string d ="99.";
string e ="00.1";
Regex r =new Regex(@"^/+?((100(.0+)*)|([1-9]?[0-9])(/./d+)*)$");
Console.WriteLine("x match count:"+ r.Matches(x).Count);//1Console.WriteLine("y match count:"+ r.Matches(y).Count);//1Console.WriteLine("z match count:"+ r.Matches(z).Count);//1Console.WriteLine("a match count:"+ r.Matches(a).Count);//0Console.WriteLine("b match count:"+ r.Matches(b).Count);//1Console.WriteLine("c match count:"+ r.Matches(c).Count);//1Console.WriteLine("d match count:"+ r.Matches(d).Count);//0Console.WriteLine("e match count:"+ r.Matches(e).Count);//0
//匹配0到100的数。最外层的括号内包含两部分“(100(.0+)*)”,“([1-9]?[0-9])(/./d+)*”,这两部分是“OR”的关系,即正则表达式引擎会先尝试匹配100,如果失败,则尝试匹配后一个表达式(表示[0,100)范围中的数字)。
(6)特殊字符的匹配
下面提供一些简单的示例:
Codestring x ="//";
Regex r1 =new Regex("^////$");
Console.WriteLine("r1 match count:"+ r1.Matches(x).Count);//1Regex r2 =new Regex(@"^//$");
Console.WriteLine("r2 match count:"+ r2.Matches(x).Count);//1Regex r3 =new Regex("^//$");
Console.WriteLine("r3 match count:"+ r3.Matches(x).Count);//0
//匹配“/”string x ="/"";Regex r1 =new Regex("^/"$");Console.WriteLine("r1 match count:"+ r1.Matches(x).Count);//1Regex r2 =new Regex(@"^""$");
Console.WriteLine("r2 match count:"+ r2.Matches(x).Count);//1
//匹配双引号
(7)组与非捕获组
以下提供一些简单的示例:
Codestring x ="Live for nothing,die for something";
string y ="Live for nothing,die for somebody";
Regex r =new Regex(@"^Live ([a-z]{3}) no([a-z]{5}),die /1 some/2$");
Console.WriteLine("x match count:"+ r.Matches(x).Count);//1Console.WriteLine("y match count:"+ r.Matches(y).Count);//0
//正则表达式引擎会记忆“()”中匹配到的内容,作为一个“组”,并且可以通过索引的方式进行引用。表达式中的“/1”,用于反向引用表达式中出现的第一个组,即粗体标识的第一个括号内容,“/2”则依此类推。string x ="Live for nothing,die for something";
Regex r =new Regex(@"^Live for no([a-z]{5}),die for some/1$");
if (r.IsMatch(x))
{
Console.WriteLine("group1 value:"+ r.Match(x).Groups[1].Value);//输出:thing}//获取组中的内容。注意,此处是Groups[1],因为Groups[0]是整个匹配的字符串,即整个变量x的内容。string x ="Live for nothing,die for something";
Regex r =new Regex(@"^Live for no(?<g1>[a-z]{5}),die for some/1$");
if (r.IsMatch(x))
{
Console.WriteLine("group1 value:"+ r.Match(x).Groups["g1"].Value);//输出:thing}//可根据组名进行索引。使用以下格式为标识一个组的名称(?<groupname>…)。string x ="Live for nothing nothing";
Regex r =new Regex(@"([a-z]+) /1");
if (r.IsMatch(x))
{
x = r.Replace(x, "$1");
Console.WriteLine("var x:"+ x);//输出:Live for nothing}//删除原字符串中重复出现的“nothing”。在表达式之外,使用“$1”来引用第一个组,下面则是通过组名来引用:string x ="Live for nothing nothing";
Regex r =new Regex(@"(?<g1>[a-z]+) /1");
if (r.IsMatch(x))
{
x = r.Replace(x, "${g1}");
Console.WriteLine("var x:"+ x);//输出:Live for nothing}string x ="Live for nothing";
Regex r =new Regex(@"^Live for no(?:[a-z]{5})$");
if (r.IsMatch(x))
{
Console.WriteLine("group1 value:"+ r.Match(x).Groups[1].Value);//输出:(空)}//在组前加上“?:”表示这是个“非捕获组”,即引擎将不保存该组的内容。
Codestring x ="Live for nothing,die for something";
Regex r1 =new Regex(@".*thing");
if (r1.IsMatch(x))
{
Console.WriteLine("match:"+ r1.Match(x).Value);//输出:Live for nothing,die for something}Regex r2 =new Regex(@".*?thing");
if (r2.IsMatch(x))
{
Console.WriteLine("match:"+ r2.Match(x).Value);//输出:Live for nothing}
Codestring x ="Live for nothing,die for something";
Regex r1 =new Regex(@".*thing,");
if (r1.IsMatch(x))
{
Console.WriteLine("match:"+ r1.Match(x).Value);//输出:Live for nothing,}Regex r2 =new Regex(@"(?>.*)thing,");
if (r2.IsMatch(x))//不匹配{
Console.WriteLine("match:"+ r2.Match(x).Value);
}//在r1中,“.*”由于其贪婪特性,将一直匹配到字符串的最后,随后匹配“thing”,但在匹配“,”时失败,此时引擎将回溯,并在“thing,”处匹配成功。在r2中,由于强制非回溯,所以整个表达式匹配失败。